Defense Tech: Brit S-92s Falling Short on Range


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Edited by Christian Lowe \| Contact

Brit S-92s Falling Short on Range

An alert DT reader forwarded this article to me from a British news service.

New search-and-rescue helicopters serving remote parts of the Highlands have yet to carry out a long-range rescue - eight months after being brought into service.

There have been problems with the multimillion-pound aircraft over the use of long-distance fuel-tanks.

The Maritime and Coastguard Agency (MCA) has insisted the problems have all been resolved, saying the tanks are now fully operational.
But crews are understood to be unhappy about the loss of seating for casualties on the aircraft in order to accommodate the tanks.

Problems surrounding the fitting of the tanks have meant the four Sikorsky S92s based at Stornoway on Lewis and Sumburgh on Shetland have been unable to carry out non-stop rescues to the range which was originally heralded.

They are, in fact, covering half the distance.

The two helicopters at Sumburgh do not have the tanks - which double their range to 400 nautical miles - fitted, while those at Stornoway, where the extra distance is most needed, are yet to carry out a rescue using them.

The MCA confirmed there had been issues over fitting the tanks.
Crewmen and spokesmen at both Stornoway and Shetland Coastguard have confirmed the tanks are "not operational" yet, despite the MCA's insistence that they are.

An interesting development for sure, but hardly an indictment on the aircraft itself. Problem is, when Sikorsky is fighting tooth and nail to get back in the running on the CSAR-X contract, news like this can't help.

More...

The first S92s were introduced in Stornoway in October, and then in Shetland in November.

Some crew are also understood to be unhappy with the tanks because they halve the seating on the craft and have questioned whether they should be used.

One source said it was a "Catch 22 situation", adding: "Do you swap the extra miles for less room for casualties, so you rescue fewer people?

The tanks have cut the seats from seven to just three."
The problems first surfaced in March when a Stornoway-based helicopter was unable to rescue an injured crewman because it was out of range.

Instead, an RAF helicopter from Lossiemouth had to fly an extra round trip of 250 miles to rescue the Russian seaman, 185 miles off Benbecula -- ironically landing him at Stornoway where the new Sikorsky S92 is based.

(Thanks to the anonymous tipster for the gouge)

-- Christian

Comments

Just for the memories... I found from a past post of Mr. Foskey that he already explained that S-92 is NOT an S-70 derivative.

Posted by: ghemago at July 11, 2008 01:23 PM

A single example of the commercial utility version, a Mk 510, is in service with the Tokyo Metropolitan Police Agency.

http://www.aeroflight.co.uk/types/international/agwest/EH101/eh-0071.jpg

Posted by: rapier at July 9, 2008 02:54 AM

Mr Foskey, on my side I'm not involved anyway with the EH-101 program or AW, it's just engineering apreciation for a well balanced product.
For the S-92 I see it like a grown-up S-70 if I remember well its origin so I have a general refrain to it, but possibly you could help me change this view.

Yes S-92 should have much more civil operators. The EH-101 is quite a big beast built for the military market and thus suffering features and then costs not apreciated by the bean counters. I would be very surprised to see the EH-101 in good numbers in the civil market, but, as you, I have no data.

Posted by: ghemago at July 9, 2008 02:31 AM

Well, far be it for me to be completely unbiased in my opinion seeing as how I was an engineer on the H92 program for 4 years.

One question for you guys, what civilian operators are flying the EH101? I honestly dont know.

Posted by: C. Foskey at July 8, 2008 08:14 PM

Mr Foskey, I was aware that I had 2 different charts but I tried to compensate.
Would you agree that the 3000 lbs of usefull load (not considering crew and fuel and standard mission equipment) I considered can more than match the "*no* TOS/loiter time, *no* HOGE time to rescue each survivor, and to top it all off they list a 20 min reserve instead of 30 min" difference?

Anyway the chart you propose for EH-101 SAR is more appropriate and I understand that the countinuos line is for the 4 tanks option while the interrupted one is for the 5 tanks option. Both options are not using any cargo space or involve external tanks. Just in case you need more range you could add optional cabin tank that can add up to 25% more as the S-92 does in this article description.

Since unfortunately there is no mission profile we can just get the numbers as:
- 360 nm with 5 rescuees 4 tanks
- 400 nm with 5 rescuees 5 tanks
and this should compared to 190 nm for the S-92 also on internal. Even factoring some mission profile difference we are still in the 1 to 2 range.

Also in all those discussions we are not factoring the specific SAR equipment standard on each helicopter.
Finally, the EH-101 has a much greater load capability that can come very handy if tou need to rescue all the crew of a cargo ship sinking.

As Mr.Alberto and I have been saying, they are different class of helicopters, this is the real apples to oranges.
Both will find their market but for the moment let's enjoy this.

Posted by: ghemago at July 8, 2008 02:38 PM

Dear Mr Foskey, no, I can't understand the chart you mention, but it report on the left side "numbers of survivors". Really I can't what this chart refer, but perhaps not the range in nm..... I'll try to investigate further regarding this quite strange chart.
Regards
Alberto

Posted by: Alberto at July 8, 2008 10:55 AM

I found, buried in the AW101 borchure, a chart (with unlabeled X-axis and chart plot lines) showing a much more applicable data set relative to the SAC chart you mentioned.

See page 17, bottom
http://www.agustawestland.com/dindoc/AW101_SAR%20CSAR_web.pdf

I am assuming the X axis is range in Nm, and the lines are internal/aux fuel, or perhaps TEO. The 101's range for SAR (and this excludes a 15 min search time like the SAC chart) looks like 360Nm internal fuel, and 390Nm aux fuel (or TEO). Also note, this chart is calculated for 2 survivors every 3 minutes, equating to only 7.5 minutes TOS for 5 survivors (hardly realistic IMHO). Recall the SAC chart range was calculated with 5 minutes per survivor, equalling 25 min TOS.

So triple the TOS (with greater hover fuel burn), add another 15 minutes to the total mission time, and then figure the max range...probably a good amount less than the listed 360Nm. Who knows what reserve they used in that chart either!

Interesting numbers indeed.

Posted by: C. Foskey at July 8, 2008 09:13 AM

Dear Mr Foskey, the last comment was from Mr Ghemago, but I'm totally agree with him. In no way you can demostrate that S-92 SAR is able to perfom the same missions of AW-101. Simply, this is NOT possible, as they are two different class of helos....
Perhaps we can consider the S-92 againt the NH-90, but NH-90 still is not in duty, even if the first helos are reaching the respective owners. We have to wait to see if S-92 will perform better than NH-90 in this role. It can't do it against AW-101, and perhaps the Canadian could confirm this, as they are using AW-101 in SAR role with extraordinary performances (obviously, waiting for the CH-148 Cyclone........ waiting, and waiting....)
Best regards
Alberto

Posted by: Alberto at July 8, 2008 09:11 AM

Alberto,

Apples to oranges. The SAC chart you are referencing is not a max range chart, it is a mission profile chart, showing range for a Search AND Rescue complete mission. The chart that AgustaWestland is showing is a mere range chart.

Sikorsky's chart numbers are calculated as "real world" range on a SAR mission; Takeoff with crew and fuel, *15 minute search*, Hover OGE @ 5 min per survivor, and a 30 minute reserve.

The AW chart mentions *no* TOS/loiter time, *no* HOGE time to rescue each survivor, and to top it all off they list a 20 min reserve instead of 30 min.

It is no wonder the numbers you pasted differ so greatly!

While I am not arguing that the 101 has greater range, or that is indeed has better performance, it must be known that the common perception of the actual performance delta between these two craft tends to be highly overplayed when objective data is closely examined.

Posted by: C. Foskey at July 8, 2008 08:44 AM

Mr Foskey, I did some research and found from the websites you listed the following data.

For the S-92 SAR version (not the executive...) I found from available graphs:
- 190 nm to rescue 5 people on internal tanks.
- 340 nm to rescue 5 people on external tanks.

For EH-101 TT (didn't find the SAR specs and the Naval are for a much heavier helicopter avionic equipment):
- 630 nm with 3000 lbs of payload excluding fuel on 5 internal tanks
- 700 nm with 3000 lbs of payload excluding fuel on 5 internal tanks using 2 engines on cruise

With one engine inoperative EH-101 can lift-off at 14300 Kg that is still 2000 Kg more than what S-92 can do with full power available.

Posted by: ghemago at July 8, 2008 08:15 AM

Alberto,

From each manufacturer's published data:

AW101 Maximum Range: 500nm (Naval) 750nm (Military)
http://www.agustawestland.com/products01_02.php?id_product=7&id=7

S92 Maximum Range: 539nm
http://www.sikorsky.com/sik/products/commercial/s92/s92_family.asp

AW101 Best Range fuel burn: 1650 lb/hr
S92 fuel burn: 1270 lb /hr

Posted by: C. Foskey at July 7, 2008 02:45 PM

Dear Mr Foskey, regarding the range of AW-101 (or EH-101 if you prefer) and the S-92:
AW-101 = 1389 Km (maximum range, 5 tanks);
S-92 = 740,800 Km (400 nm)
So, it seems that S-92 is quite shorter versus AW101.......
Regarding performance, also here and with the 3 engines, AW-101 has greater (and not of few....) performances.
Really, in my opinion, we will not have to compare Aw-101 with S-92. They are in a different scale (obviously also regarding the cost, AW-101 is expensive......).

Best regards
Alberto

Posted by: Alberto at July 7, 2008 10:36 AM

@ Davide

Id love to see where the EH-101 is getting double the range as the S-92 on internal fuel with 3 turbines.

@ Ghemago

Raw performance is actually a lot closer than you think, and the 92 even bests the 101 in hover ceiling OGE and IGE. Also, factor in the 3rd turbine, and the maintenance (MTBF, TTO) and operating costs (fuel) play a significant factor.

Posted by: C. Foskey at July 6, 2008 03:16 PM

Mr Foskey, thanks a lot for your answers. My feeling is that the S-92 is a good airplane when used for what was designed for. In the oil business work where it doesn't stretch the range, S-92 is earning the wings but when is oversold because Sikorsky hasn't a bigger chopper to propose, then it hurts the whole image.
As always is, it's a matter of the right tool for the right job.

Davide, I guess the response lies in the euros you need to buy an EH-101... If you compare raw performances it's no brainer.

Anyone has price ranges for the S-92 and EH-101 in similar avionic suites possibly coming from a real competition? I do expect a big advantage on the S-92...

Posted by: ghemago at July 5, 2008 07:08 AM

Hi all,
interesting discussion...
My question is: why have they decided to buy the Sykorsky helo instead of the EH-101? 3 engines with max range doubled respect to the S-92, I think it's better and more secure for SAR and CSAR missions on sea!
It was selected by many oil companies that have offshore platform in the North Sea due to its security...

Posted by: Davide at July 5, 2008 03:16 AM

Dear Mr Foskey, thank you very much for your very interesting replies. To comment them:
1) Well, if the MCA decided to have the S-92 in this role, it was ALSO due to the fact that the range of the helo can be extended by external/addititional tanks. And this was justified, as now we have that they failed to complete some mission..... at least we have to consider that this helo is still not ready to do his work.
2) Your informations are really interesting, we will wait official report from Sikorsy to know when (or if) such problems will be solved and when the first helos will enter service.

Best regards and sorry for my poor english.
Alberto

Posted by: Alberto at July 5, 2008 02:08 AM

Alberto, Im glad to input anything I can.

1.) If you carefully read the article you'll notice it mentions the S92 is covering half the distance "originally heralded" because the originally heralded max range was WITH the aux fuel tanks installed. It sounds like the piece was written to stir up doubt about the aircraft itself, when in reality it should be raising concerns about the logistic capability of the MCA to outfit their AC for their mission requirements. However, I am unsure as to why they are having difficulty with the tank installations.

2.) I spent 2 months doing liaison work in Keystone PA where the first CH-148 AC were undergoing final cabin assembly. I was involved with numerous production modification designs from the base S92, including the RAST, troop seats, search radar, weapons pylon, and other items. From my time on the shop floor, we ran into no serious issues. After cabins are completed they are sent to West Palm Beach for final assy and flight testing. The schedule was still in place when I left PA in Feb, to have delivery in Jan 09. However, this was from the airframe POV. The thing that worried me was the FBW S92 maiden flight was completed only in late 2007. There may be issues getting this into production AC, but I am not sure about that. My S/H92 time came and went.

Posted by: C. Foskey at July 4, 2008 12:35 PM

It's really a pleasure to hear you again Mr Foskey !!!! Your "inside" comments are really precious to reinstate the thrut about such matters involving the S-92 !
So, just two questions:
1) In you opinion, as there is no any problem about fuel charge of S-92, why it was not able to complete SAR missions assigned ?
2) from a previous thread, could you please advise us exactly WHEN Canda will receive their CYCLONE helos ?

My best regards
Alberto

Posted by: Alberto at July 4, 2008 07:39 AM

My best regards
Alberto

Posted by: Alberto at July 4, 2008 07:27 AM

My best regards
Alberto

Posted by: Alberto at July 4, 2008 07:23 AM

Hi Mr Foskey, what a pleasure to hear you again ! Your "inside" postion could help us to understand some thing about two matters.
1) If is not true that S-92 is short on range, why is actually unable to perform the whole missions ?
2)......from another post, could you please advise exactly WHEN Canada will receive their CYCLONE helos ????

My best regards Mr Foskey
Alberto

Posted by: Alberto at July 4, 2008 05:10 AM

Any chance we can be the British in your articles are not the "Brits"; this started out as a derogatory term in NI. Same way we don't use the term "Yanks" in polite conversation.

Apart from that interesting piece; note we didn't buy homegrown and ask for a government enquiry into why Augusta-Westland lost; maybe the best helicopter was chosen.

Posted by: Matt at July 3, 2008 07:20 AM

"IIRC, the Russians have sea planes for this mission, which have much greater range than helicopters. While sea planes are a niche application, I'm surprised that there aren't more in Western military and civil defense forces."

The biggest problem with sea planes is that they can only land in relatively calm water. We used them in WWII because we had no better alternative. The arrival of helicopters made them basically obsolete. Helicopters can hover over the water and raise/lower people and cargo while remaining (relatively) safely out of the range of the waves. Anything beyond a mild chop would swamp any seaplane that touched down. The helicopter can also land and takeoff at any location with a small patch of flat ground, whereas seaplanes require runways (if they have landing gear) or special facilities on the shore that would result in an additional leg of the journey for any wounded occupant.

Posted by: ADyer at July 2, 2008 03:51 PM

By itself, this should not be an issue for the CSAR-X competition. You're not likely to be going after more than a couple pilots per sortie.

Posted by: Will at July 2, 2008 02:58 PM

Nothing in the article suggests that the 92 is falling short on range whatsoever.

Max fuel on standard tanks: 2327 kg
Max fuel on auxillary tanks: 3460 kg

Max range:
457 Nm - standard fuel, 30 min reserve.
759 Nm - aux fuel, 30 min reserve
241 Nm radius of action on standard fuel, 30 min reserve, 2 survivors.

Average fuel burn in 2000´:
580 kg/hr

Nobody said the AC itself is having range problems. I dont see how you can expect the AC to make its max aux fuel range without aux fuel tanks installed!

Posted by: C. Foskey at July 2, 2008 02:33 PM

correction. my sentence should be: "Given the climate and nature of the Highlands and Hebridies, the MCG and the Royal Coast Guard should not fool around with reporting the completion of fuel tanks and such, and the a/c manufacturer should not fool around with range estimate. "

Posted by: coviepresb1647 at July 2, 2008 11:04 AM

Christian,

Why not post the entire article, or link to it? Your excerpt leaves out some information.

http://www.pressandjournal.co.uk/Article.aspx/714607?UserKey=0

PS. Your pic is of S92 prototype AC3, I believe, not a British SAR S92.

Posted by: C. Foskey at July 2, 2008 08:52 AM

As a designer on the S/H92 program, I am surprised to hear these comments about seating going from 7 to 3. The 2 cabin mounted aux fuel tanks leave room for 8 pax and a triple litter kit.

Have a look:
http://www.geocities.com/cefoskey/cabin.JPG

There was a design study for CSARX which used sponson mounted aux tanks (a la CH53), however I believe it interfered too much with field of fire. For SAR, the only concern was drag on Vbr, which would not have been much.

Posted by: C. Foskey at July 2, 2008 08:37 AM

The S-92 is designed and is used (various companies) to make haul people and equipment to offshore oil rigs, specially in the North Sea. Baffling that problems have occured - the Canadians have also had problems.

Posted by: samuraipizza at July 2, 2008 08:26 AM

@ohwilleke

A sea plane wouldn't cut it for the job these guys are doing, as they need the ability to hover & winch casualties aboard.

They are also used for mountain rescue.

Posted by: fnool at July 2, 2008 04:50 AM

IIRC, the Russians have sea planes for this mission, which have much greater range than helicopters. While sea planes are a niche application, I'm surprised that there aren't more in Western military and civil defense forces.

Posted by: ohwilleke at July 2, 2008 03:00 AM

Hmmmmm,this is one of the helicopters being considered for CSAR duty with the Air Force. It really does make the H-47 Chinook look like the right choice to begin with by the Air Force.

Posted by: Roy Smith at July 2, 2008 12:13 AM

Stornoway isn't part of the Highlands but the Hebridies. Given the climate and nature of the Highlands and Hebridies, the MCG and the Royal Coast Guard should not fool around with reporting the completion of fuel tanks and such, and the a/c manufacturer should fool around with range estimate. I would hate to be in the Highlands between Halkirk and Ullapool and have to trust my life to an a/c that doesn't have confidence in its range.

Posted by: coviepresb1647 at July 1, 2008 07:36 PM

Brit S-92s Falling Short on Range

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